Jonathan Golub, chief U.S. equity strategist at Credit Suisse, said the rally may be overdone.

"I think that we're overplaying the near-term news. If there was absolutely no news of a vaccine, the stock market would probably be up [Monday] the same way that it's been up the last, you know, month or more. And this is really a story of a huge amount of liquidity and stimulus coming from the government. And if you look at the overall news flow, I'm not sure that it would by itself warrant the kind of move that we've had right here."

"This is a really big week for earnings. Huge. Walmart is a dominant stock and psychologically Home Depot, Lowe's, Target really matters. Oh by the way, all the people who felt that certain stocks that have been doing well are going to start selling off, I go back to Nvidia. It reports this week but there's no sign that Nvidia is done -- in part because there's a big gaming cycle and in part because they have those inference chips, the ones that really can actually understand slang. … The Achilles' heel of this market that nobody talks about, it's not the cruise ships, it's not some retail, it's Wells Fargo. It's the banks, and they're screaming today. And I think that really matters … their stocks are saying default, default, default."

Samantha Azzarello, global market strategist at J.P. Morgan Asset Management, said there's a disconnect between the economy and markets.

"I think the volatility right now is tied to a bunch of different things whether we're going up or going down -- right it's vaccine news, it's treatment news, it's Jay Powell speaking, we know that. I still think though there's a little bit of a disconnect between the real side of the economy and what's happening with the macro data, in particular the labor market, and then what's happening on the financial side just given that spreads have tightened which is obviously good, the market is up, which is good, and conditions are loose so I think we're just monitoring that gap between one and the other to kind of see where things go over the next couple months."

David Harden, president of Summit Global Investments, said certain names may have run too far, too fast.

"From a standpoint of the market fundamentals, what earnings are happening, we have companies that are not earning as much as they need to, they're having struggles with employment. We have 35 million-plus people unemployed right now. That's the economy, that's the reality of the fundamentals. When you have companies like Zoom, which is more than all seven of the top airlines combined, its valuation is very, very large. … I think you do have some companies that are overextended in this market."

"Equity is pricing in the best-case scenario here which for myriad reasons is not something that I can get behind. Credit, however, is pricing in somewhere between sort of a downside second wave, maybe we haven't hit a low and the base-case scenario, which is that we keep on slowly going up from here."